Leslie Kean's UFOs

I've been reading Leslie Kean's marvelous book, UFOs. I highly recommend it for anyone who is interested in UFO lore--the notes on sources alone are worth the time and money. Last night, I read one comment that set me to thinking. She mentions the possibility of solving "the mystery" of UFOs. I wonder if it's possible to solve that particular mystery to everyone's satisfaction. Some, of course, regard it as already solved, one way or the other; but if UFOs are, as some believe, alien spacecraft, then I think there is a good chance no one will ever be able to prove to everyone's satisfaction that they are. If UFOs are in fact alien in origin, then they have probably been visiting this planet for decades, if not centuries or millennia. In that case, we may well have all the evidence we're ever going to get--sighting reports, the odd bit of puzzling metal or altered vegetation from a landing site, radar data, and rumors about a crashed saucer in some government warehouse. Of course, if a saucer crashes in Central Park and CNN covers the aliens staggering from the smoking remains, I guess that will count as final proof. But failing that, we will continue to debate and speculate.

Personally, I find some of the stories about what UFOs are capable of to be fairly strong evidence that they may be alien spacecraft. But I don't completely rule out the possibility that they are terrestrial aircraft. Take the triangular or boomerang-shaped UFOs reported in Hynek, Imbrogno, and Pratt's Night Siege. Reliable witnesses say the craft hovered silently or nearly silently and moved silently at very low altitude. This much could be explained if the craft were a lighter-than-air vehicle, but how would such a craft be propelled? No one reported propellers or exhaust, so one is forced to speculate that something like the ion drive (nmp.nasa.gov/ds1/tech/ionpropfaq.html) used for some spacecraft might be employed. At this point, of course, we have entered the realm of sheer speculation about hypothetical secret aircraft.

Occam's Razor is a key principle to keep in mind here. Occam's Razor, of course, says that the simplest explanation of a phenomenon is probably the best and closest to the truth. So which is simpler--that aliens have visited the Earth, or that a secret aircraft is roaming the night skies for no clear and discernible reason? Looks like a toss-up to me.